Cryptic Biological Invasions: a General Model of Hybridization

Abstract

The dispersal of non-native genes due to hybridization is a form of cryptic invasion with growing concern in evolution and conservation. This includes the spread of transgenic genes and antibiotic resistance. To investigate how genes and phenotypes are transmitted, we developed a general model that, for the first time, considers concurrently: multiple loci, quantitative and qualitative gene expression, assortative mating, dominance/recessivity inheritance and density-dependent demographic effects. Selection acting on alleles or genotypes can also be incorporated. Our results reveal that the conclusions about how hybridization threatens a species can be biased if they are based on single-gene models, while considering two or more genes can correct this bias. We also show that demography can amplify or balance the genetic effects, evidencing the need of jointly incorporating both processes. By implementing our model in a real case, we show that mallard ducks introduced in New Zealand benefit from hybridization to replace native grey-ducks. Total displacement can take a few generations and occurs by interspecific competition and by competition between hybrids and natives, demonstrating how hybridization may facilitate biological invasions. We argue that our general model represents a powerful tool for the study of a wide range of biological and societal questions.

Identifying hybrids & the genomics of hybridization: Mallards & American black ducks of Eastern North America

“…However, despite these rates, we find that pure black ducks remain on the landscape. Thus, while hybridization may be quite prevalent, such acts may simply be wasted reproductive effort (Leonard, Echegaray, Randi, & Vilà, ; Quilodrán, Austerlitz, Currat, & Montoya‐Burgos, ) as gene flow via backcrossing appears to be somehow limited. We predict that hybrids are somehow maladaptive as compared to their parentals, and perhaps assortative mating based on plumage or other characteristics by parentals maintains lower levels of actual gene flow between mallards and black ducks.…”

Hybridization and introgression during density‐dependent range expansion: European wildcats as a case study

“…Hybridization has been shown to have the potential to facilitate biological invasions and result in the decline of native genotype or the extinction of one or both parental species (Quilodrán et al. , , ).…”

Conservation of adaptive potential and functional diversity: integrating old and new approaches

“…Genomic studies have dramatically expanded on such views; signatures of introgression have been found more widely than expected and hybrid speciation even in diploids has been resurrected as a driving force in evolution that could have important conservation implications (e.g. Robinson et al 2016;vonHoldt et al 2016vonHoldt et al , 2017Quilodran et al 2018;Smith et al 2018).…”